INI / Registry Router

What

n_cst_appmanager

Why

PowerBuilder applications are often deployed to multiple platforms:

Windows 95/NT/3.1, Macintosh, UNIX. Windows95 and Windows NT applications can use the registry to store application and user settings, whereas other platforms must rely on INI files.

Determining where to obtain these settings can result in redundant code. (For example, look in pfc_w_master's open event. There is quite a bit of code for the preference service to restore the user's last settings. Similar redundant code is found in the close event to save the settings.)

Furthermore dynamically changing the source of the application and user settings requires overriding the of_isRegistryAvailable() function to change it's original meaning.

How

4 polymorphic functions are included to determine where to obtain application and user settings:

 public function string of_getappvalue (string as_section, string as_label, string as_default)
 public function boolean of_setappvalue (string as_section, string as_label, string as_value)
 public function string of_getuservalue (string as_section, string as_label, string as_default)
 public function boolean of_setuservalue (string as_section, string as_label, string as_value)

These functions merely check the is_source instance variable, which determines the appropriate source for the requested setting. For example, here's the code for of_getAppValue():

 /*
 Return value of a specified label from either 
 Windows registry or the application's INI file.
 */ 
 
 string ls_registryValue 
 
 IF is_source= "registry" THEN
	IF NOT of_getAppRegistryValue(as_section, as_label, ls_registryValue) THEN
		RETURN as_default
	ELSE
		RETURN ls_registryValue
	END IF
 ELSE
	RETURN of_getAppProfileString(as_section, as_label, as_default)
 END IF

The is_source instance variable is set in the constructor event based on whether the registry is available on the specific platform:

 /*
 Determine the initial source value.
 */ 
 
 IF this.of_isRegistryAvailable() THEN
	is_source = "registry"
 END IF

An example call would look like this:

 // Get the location of the user's log file.
 ls_logFile = gnv_app.of_getUserValue("General", "LogFileLocation", "log.txt")

Notes:

1) These functions rely on the PFC app/user key/ini settings. Make sure you call these functions in your application manager. Example:

 // constructor event
 of_SetAppKey("hkey_local_machine\software\My Company\My Application")
 of_SetAppIniFile("MyApp.ini")
 of_SetUserIniFile("MyApUser.ini")
 
 // pfc_logon event - after successful logon
 of_SetUserKey(of_getAppKey() + "\" + of_getUserId())

2) If the platform is Windows95 or Windows NT, but you want to use an INI file, you may call of_setSource("ini") to override the default source setting.

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Last Revised: February 15, 2004 03:58 AM.